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Trouble Keeping The Revs Up....


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#1 vipernewz

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Posted 22 January 2013 - 08:35 AM

Hey,

First off I have a 1989 Mini Thirty with everything pretty much standard....

Over the past week or so with this cold weather I have been having real problems on the commute to work with the car idling at around 1500rpm (with choke) then you pull away do a bit of driving and when pull up at the next junction the car then looses all revs and cuts out... Then it will cough for a bit while trying to start it back up... If you put the choke out so I'd idles at around 2000rpm it's perfectly fine, but then I'm running around with full choke all the time... And if you put the choke the whole way in it then idles around 400rpm which is too low.
The temp gage is showing that it is all heating up as usual if it would on any normal day.
Also when I apply the brake with the clutch engaged the revs drop by about 100 and then go back up if I release the brake still with the clutch still engaged ? :S

So far I have checked the oil (which was fine), topped up the radiator (just in case it was showing it was heating up too quickly) and fitted the pipe between the air filter and the warm air pipe which was missing.

Can anyone help point me in a direction of what might sort this issue?

I've got a couple of other ideas like check the thermostat and make sure it's allowing the hot water to circulate, changing the leads and rotor arm in the dizzy... And possibly have a look at the carb?

Many thanks in advance... Tom

Edited by vipernewz, 22 January 2013 - 08:36 AM.


#2 tiger99

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Posted 22 January 2013 - 08:47 AM

I would suggest starting with the carburettor, as there is no indication yet that anything else is to blame.

#3 jaydee

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Posted 22 January 2013 - 09:42 AM

Sounds like youre running lean. if you have access to a gas tester, set mixture to 2.5%-3.0% CO at idle with engine warm

#4 Wil_h

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Posted 22 January 2013 - 11:28 AM

As it is only recent and in this cold damp weather it's almost definately carb icing, and there's not too much you can do about it.

As for the brake, I assume you have a servo?

#5 Mini Mad Drakeley

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Posted 22 January 2013 - 11:34 AM

sounds sorta like a problem i was having recently, check that the pipe going from the breather on the back of the engine to the carb is fitted properly and also the pipe going from the vacuum on the distributor to the carb doesnt have any leaks or anything

Adam

#6 vipernewz

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Posted 22 January 2013 - 12:27 PM

sounds sorta like a problem i was having recently, check that the pipe going from the breather on the back of the engine to the carb is fitted properly and also the pipe going from the vacuum on the distributor to the carb doesnt have any leaks or anything

Adam

Hey Adam,
I recently changed the pipe from the breather to the carb which was missing >.< and have checked the pipe from the vaccum which didnt show any signs of leaks...

As it is only recent and in this cold damp weather it's almost definately carb icing, and there's not too much you can do about it.

As for the brake, I assume you have a servo?

Yes I do have a servo for the brakes

I would suggest starting with the carburettor, as there is no indication yet that anything else is to blame.

Thanks Tiger... think I might have to take it to a garage as I have never played around with the carb dont want to mess things up :P

#7 JonnyBMX

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Posted 22 January 2013 - 12:47 PM

have you tried the advance retard pipe? should go from the front of the carb to the distributer unless thats what your talking about when you say vacum pipe? i fixed a mini with similar diagnosis recently when this pipe was split

#8 vipernewz

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Posted 22 January 2013 - 01:00 PM

have you tried the advance retard pipe? should go from the front of the carb to the distributer unless thats what your talking about when you say vacum pipe? i fixed a mini with similar diagnosis recently when this pipe was split

Please excuse my lack of knowledge of distributor parts, but off the side of the dizzy you have a disc? and the pipe that leads from that to the carb is fine... not sure which part that is :P thought it was the vaccum but could be wrong.

#9 JonnyBMX

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Posted 22 January 2013 - 02:45 PM

yeah thats the advance/retard pipe :) but you are right it is a vacum :)

#10 Wil_h

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Posted 22 January 2013 - 05:43 PM


As it is only recent and in this cold damp weather it's almost definately carb icing, and there's not too much you can do about it.

As for the brake, I assume you have a servo?

Yes I do have a servo for the brakes


Then check the feed to it from the manifold for an air leak.

#11 vipernewz

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Posted 22 January 2013 - 06:32 PM

Ok update... on the drive home from work today I have now realised (thanks to some idiot in a sporty Renault pulling out on me) that it definitely is something to do with brakes. After being cut up and experiencing a dramatic drop in revs, I then done some brake testing on the way home and if I slow down with little or no brakes then its all fine. If I brake then it all goes wrong... will drop to 2-300 revs then tap the accelerator and it will sit at 1000.

So thank you Wil, going to check the servo unit once I can find a bloomin torch >.<




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